U of S team finds link between seals and wild horses

What do grey seals and Sable Island horses have in common? The University of Saskatchewan knows.

Biologists at the U of S have learned important new details explaining the growth ofwild horse populations on the small island, located about 175 kilometres southeast of Nova Scotia, and they say much about how life is interconnected.

Sable Island is truly one of the most interesting outdoor laboratories.- Philip McLoughlin

A team led by Philip McLoughlin and Keith Hobson set out to answer an important question. Why has the population of wild horses on the island reached a record high of 450 to 550? After all, the population had held steady at 200 to 400 horses for centuries.

What they found is a link between grey seals and the foraging habit of the horses. The research is featured in the journal Ecology and in The Scientist.

Where land and sea meet

Grey seal populations are on the rise, and when they have pups on the shore, they fertilize the sandy grasslands. Nutrients from the sea are helping the grass to grow and so the horses are well fed.

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"What is really interesting is that we show how the enrichment of grasses, which occurs non-uniformly on the island, then affects how the horses move around the island to eat," said McLoughlin.

"This speaks to the question of how seemingly distinct systemsocean and landcan be interconnected by fundamental ecological relationships."

The U of S team suggested that more work needs to be done to prove the link between thriving seals and the increasing survival and population growth of the wild horses.

The next step is to try and detect sea nutrients in the tissue or hair of the horses.